How to bind a variable with field on work order page

Summary:

Hello Experts,

I need some help from VBS expert. We have a custom button on Customer Work Order page in Fusion Service which cancels the work order. We want to add a condition to check if the Cancel Reason field is empty, it would display an error message and do not perform further action. The Cancel Reason field is a OOTB field which is exposed on the work order layout.

I have added a below code line into the Action Chain which is linked to the Cancel WO button. However, since the cancelReason variable is not bound to the field, it still shows the error message even when the field is filled.